COCHISE Pilot Study: Closed vs Open Cells Stent for High Risk Percutaneous Coronary Interventions in ST Elevation Acute Myocardial Infarction

BACKGROUND Primary percutaneous coronary intervention (PPCI) represents the "gold standard" in the current management of patients with acute ST-elevation myocardial infarction (STEMI). Indeed, PPCI is associated with a rapid restore of coronary flow and with a better outcome compared to pharmacological therapy. However in a sizable proportion of patients PPCI achieves only epicardial coronary artery reperfusion but not myocardial reperfusion, a condition known as no-reflow. A series of consistent data has clearly shown that no-reflow has a strong negative impact on outcome, negating the potential benefit of PPCI. No-reflow may be caused by the variable combination of 4 pathogenetic components: 1) distal atherothrombotic embolization; 2) ischemic injury; 3) reperfusion injury; and 4) susceptibility of coronary microcirculation to injury. In particular during PPCI emboli of different sizes can originate from fissurated atherosclerotic plaques and occlude the microvascular bed. Several pharmacological, mechanical or technical strategies have been proposed for the prevention and treatment of distal embolization and coronary no-reflow with variable results, but there are no data addressing the possible effect of different stent designs on the distal embolization of thrombotic fragments.

Coronary stents can be divided in open cell or closed cell stents according to their design. Typically, the number and arrangement of bridge connectors differentiate open-cell from closed-cell designs. If adjacent ring segments are connected at every possible junction, the design is classified as closed cell. If some or all of the connecting junction points are removed, the design is classified as open cell. Such a design inherently allows for more flexion between adjacent rings, because fewer connection points allow for greater flexion and conformability. The flexion benefits of an open-cell design have a cost in scaffolding uniformity, just as the scaffolding benefits of a closed-cell design have a cost in flexion and conformability. A previous study, performed in patients who underwent carotid stenting, showed a significant reduction in distal embolization associated with the use of closed cell stents compared to open cell stents. However there are no study comparing the open or closed stent design during percutaneous coronary intervention particularly in condition at high risk of embolization as acute myocardial infarction.

STUDY HYPOTHESIS AND OBJECTIVES The aim of this study is to determine whether a closed cell stent design may reduce distal embolization and no reflow during PPCI for acute STEMI compared to an open cell stent design. The study population will include all consecutive patients admitted in our hospital for acute STEMI and treated with PPCI within 12 hours from symptom onset.

METHODS Design This study will be a prospective, randomized trial.

Patient selection Eligibility criteria: patients with an age > 18 years with acute STEMI treated with PPCI within 12 hours from symptom onset and who agree and provide written informed consent. STEMI is defined as chest pain associated with ST-elevation of 1 mm or more in two or more contiguous leads or new left bundle-branch block within 12 hours after the onset of chest pain.